Axial-radial two-way staged reinforced pulsed magnet
By using a bidirectional graded reinforcement structure, the problem of balancing axial and radial electromagnetic forces in radially graded reinforced ultra-strong magnetic field pulse magnets has been solved, achieving efficient magnetic field superposition and stable operation with high field strength, significantly improving the reliability and reusability of the magnets.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA ELECTRIC POWER RESEARCH INSTITUTE CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-07-21
AI Technical Summary
Existing radially graded reinforced ultra-strong magnetic field pulse magnets are difficult to balance axial and radial electromagnetic forces simultaneously, resulting in the burning or penetration of end wires through the reinforcement layer, and it is difficult to achieve a stable magnetic field of more than 100T.
The structure employs a bidirectional graded reinforcement structure along the shaft diameter. Multiple sub-magnets are stacked axially, with each sub-magnet containing two symmetrically arranged coils. The coils are composed of multiple coaxial and radially nested solenoids. The fiber winding direction of the sub-magnet reinforcement layer near the mid-plane is at a 90° angle to the magnet axis, while the fiber winding direction of the sub-magnet reinforcement layer away from the mid-plane is at an acute angle. The sub-magnets are tightly stacked at each level through insulating flanges and supports, and a high-strength fiber composite material reinforcement layer is used.
It achieves efficient superposition of magnetic fields, significantly improves the axial load-bearing capacity of the magnet, reduces the axial displacement at the end, enhances the reliability and reusability of the magnet, and can operate stably and generate high field strength pulsed magnetic fields of over 90T.
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Figure CN122436346A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of pulsed high magnetic field technology, and more specifically, to a pulsed magnet with bidirectional graded reinforcement of shaft diameter. Background Technology
[0002] Pulsed magnets are important research tools for exploring the unknown world in cutting-edge fundamental science fields such as condensed matter physics and magnetism. The higher the field strength they generate, the more obvious the effect on matter, and the greater the possibility of discovering new phenomena and laws. Therefore, the development of ultra-strong magnetic field pulsed magnets with a magnetic field of over 100T has been a long-cherished aspiration of countries around the world, and many countries, including the United States, Germany, and France, have been carrying out research and development work for more than 20 years.
[0003] Currently, all ultra-strong pulsed magnets employ a radially graded reinforcement structure. This means the magnet consists of multiple coaxial, concentric, radially nested solenoids. Each solenoid is reinforced with a high-strength Zylon fiber composite material wound around it under high tension. The thickness of each reinforcement layer is determined by the radial electromagnetic force experienced by the internal solenoid conductors. All ultra-strong magnetic field pulsed magnets currently use this structure; the differences lie only in the cross-sectional dimensions of the solenoid conductors, the number of stages, the number of turns, and the thickness of the reinforcement layers at each stage.
[0004] However, radially graded reinforced ultra-strong magnetic field pulse magnets often exhibit significant end-conductor failure, with the end conductors burning out or penetrating the reinforcement layer under conditions far below the design limit magnetic field or with extremely low discharge cycles. This failure is caused by the extremely low axial strength of the high-tension circumferentially wound Zylon fiber composite material, which struggles to balance the axial Lorentz force generated by the radial stray magnetic field at the magnet's end, resulting in significant axial displacement of the end conductors. The single circumferential winding, high tension, and the use of poorly impregnated Zylon fibers are all aimed at improving the radial load-bearing capacity of the reinforcement layer. Changing any of these factors would require increasing the reinforcement layer thickness by more than 50% to keep the maximum stress within acceptable limits. This drastically increases the energy required for magnet discharge and the maximum temperature rise, failing to meet design requirements.
[0005] Therefore, the three unconventional manufacturing processes of the aforementioned composite material reinforcement layer are a crucial requirement for balancing the enormous radial electromagnetic forces near the central plane of the magnet. However, this combination of processes results in a significantly low axial strength of the reinforcement layer, less than 25 MPa, almost completely eliminating its axial load-bearing capacity and making it difficult to balance the axial electromagnetic forces at the magnet's ends. Clearly, this defect stems from the significant difference in electromagnetic forces between the magnet's ends and the area near the central plane. A single radially graded reinforcement method for ultra-strong magnetic field pulse magnets cannot simultaneously meet the balance requirements of electromagnetic forces at all internal locations, thus limiting the stable realization of magnetic fields exceeding 100T. Summary of the Invention
[0006] In view of this, the present invention proposes a pulse magnet with bidirectional graded reinforcement of shaft diameter, which aims to solve the problem that existing radially graded reinforced ultra-strong magnetic field pulse magnets are difficult to balance axial and radial electromagnetic forces at the same time. This invention proposes a pulse magnet with bidirectional graded reinforcement of shaft diameter, comprising: A multi-level sub-magnet stacked along an axial direction, wherein the multi-level sub-magnets are symmetrically distributed about the plane in the magnet; Each of the sub-magnets comprises two symmetrically arranged coils, each coil consisting of multiple coaxial and radially nested solenoids; Each stage of the solenoid is wound sequentially from the same conductor, and each stage of the solenoid has a high-strength fiber composite material reinforcement layer on its outer surface; wherein, the fiber winding direction of the first-stage sub-magnet reinforcement layer closest to the plane of the magnet is at a 90° angle to the magnet axis, and the fiber winding direction of the remaining sub-magnet reinforcement layers is at an acute angle to the magnet axis.
[0007] Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of shaft diameter, an insulating flange is provided between adjacent sub-magnets to ensure that each sub-magnet is tightly stacked without axial gap.
[0008] Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of the shaft diameter, each coil is provided with a positive terminal connector and a negative terminal connector. The positive terminal connector is located at the end of the innermost solenoid of the coil and is connected to the positive power supply via a copper busbar nested in an insulating flange. The negative terminal connector is located at the end of the outermost solenoid of the coil and is directly connected to the negative power supply. Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of shaft diameter, the insulating flange is provided with a central through hole, the center of which is located on the magnet axis and its diameter is not less than the minimum inner diameter of each sub-magnet; the outer diameter of the insulating flange is not less than the maximum outer diameter of each sub-magnet.
[0009] Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of shaft diameter, a support member is provided between the primary sub-magnet and the secondary sub-magnets on both sides. The support member is used to provide a flat axial support surface for the portion of the secondary sub-magnet located radially outside the primary sub-magnet.
[0010] Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of shaft diameter, the coils of each sub-magnet have at least one different parameter among inner diameter, outer diameter, height, and number of solenoid stages.
[0011] Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of shaft diameter, the conductors used in the solenoids of each sub-magnet have a conductivity greater than 40% IACS and an ultimate tensile strength greater than 200 MPa.
[0012] Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of the shaft diameter, the ultimate tensile strength of the fiber material in the reinforcement layer is greater than 1 GPa.
[0013] Furthermore, in the aforementioned pulse magnet with bidirectional graded reinforcement of the shaft diameter, the sub-magnet coil reinforcement layer with a higher axial grade has a smaller average angle between the fiber winding direction and the axial direction, a thinner average thickness, a higher axial load-bearing capacity, and a lower radial load-bearing capacity compared to the sub-magnet coil reinforcement layer with a lower axial grade.
[0014] Furthermore, in the aforementioned pulse magnets with bidirectional graded reinforcement of shaft diameter, the sub-magnets with higher axial grades have larger inner diameters, outer diameters, and heights, and the conductors used in the internal solenoids have higher conductivity, lower ultimate tensile strength, and larger cross-sectional areas.
[0015] The pulse magnet with bidirectional graded reinforcement of shaft diameter in this invention consists of axially symmetrically stacked multi-stage sub-magnets, each sub-magnet containing two symmetrically arranged coils and a multi-stage coaxial and radially nested solenoid structure. This invention achieves efficient superposition of magnetic fields. The first-stage sub-magnet located near the central plane of the magnet uses circumferentially wound fibers as a reinforcing layer, effectively resisting the radial electromagnetic force in this area. The remaining sub-magnets far from the central plane of the magnet use obliquely wound fibers as a reinforcing layer, significantly improving the axial load-bearing capacity. This effectively compensates for the deficiency of insufficient axial strength in the end region caused by traditional single reinforcement methods, and also avoids the problem of passively increasing the thickness of the reinforcing layer near the magnet end to resist the huge radial electromagnetic force near the central plane of the magnet, thus reducing the contribution of the end region conductor to the central field. At the same time, each stage of the solenoid is wound with the same conductor, ensuring reliable electrical connection. Therefore, this invention not only solves the technical problem of structural damage caused by excessive axial displacement at the end of traditional pulse magnets, but also achieves stable operation and high repetitive discharge at high field strengths of over 90T, greatly improving the reliability and reusability of the magnet. Attached Figure Description
[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A half-sectional unfolded schematic diagram of a pulse magnet with bidirectional graded reinforcement of shaft diameter provided in an embodiment of the present invention; Figure 2 A schematic diagram of the discharge waveform of a pulse magnet with bidirectional graded reinforcement of shaft diameter provided for an embodiment of the invention; Figure 3A cloud map of the axial magnetic field distribution at the peak moment of a pulse magnet with bidirectional graded reinforcement of shaft diameter provided for an embodiment of the invention; Figure 4 A radial magnetic field distribution cloud map at the peak moment of a pulse magnet with bidirectional graded reinforcement of shaft diameter provided for an embodiment of the invention; Figure 5 A magnetic field waveform diagram at the center of a pulse magnet with bidirectional graded reinforcement of shaft diameter provided for an embodiment of the invention; Figure 6 Stress distribution cloud map at peak time for a pulse magnet with bidirectional graded reinforcement of shaft diameter provided for an embodiment of the invention; Figure 7 Maximum temperature distribution cloud map of a pulse magnet with bidirectional graded reinforcement of shaft diameter provided for an embodiment of the invention; Figure 8 Maximum axial displacement contour map of a pulse magnet with bidirectional graded reinforcement of shaft diameter provided for an embodiment of the invention; Figure 9 The maximum axial displacement contour map of a 100T magnet reinforced by traditional radial gradation. Detailed Implementation
[0017] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0018] See Figure 1 The pulse magnet with bidirectional graded reinforcement of the shaft diameter in this embodiment of the invention includes: multi-level sub-magnets 1 stacked along the axial direction, the multi-level sub-magnets 1 being symmetrically distributed about the central plane of the magnet; each sub-magnet 1 includes two symmetrically arranged coils 2, each coil being composed of multi-level coaxial and radially nested solenoids; each level of solenoid is sequentially wound from the same wire, and each level of solenoid has a high-strength fiber composite material reinforcement layer 3 on its outer surface; wherein, the fiber winding direction of the first-level sub-magnet reinforcement layer 3 closest to the central plane of the magnet makes an angle of 90° with the axial direction of the magnet, and the fiber winding direction of the remaining sub-magnet reinforcement layers 3 makes an acute angle with the axial direction of the magnet.
[0019] In this invention, the plane in the magnet refers to the geometric center cross-section of the pulse magnet along its axial direction, that is, the plane perpendicular to the magnet axis and passing through the midpoint of its length.
[0020] In this embodiment, the number of multi-level sub-magnets 1 is n, where n is an integer greater than or equal to 2. When n > 2, third-level sub-magnets 1, fourth-level sub-magnets, and so on can be stacked outside the first-level sub-magnet 1. Each additional sub-magnet is connected by an insulating flange, and a corresponding reinforcing layer and support structure are set according to the radial or axial electromagnetic force at its location. The multi-level sub-magnets are symmetrically distributed about the central plane of the magnet. The k-th level sub-magnet located above the central plane has the same geometric dimensions as the k-th level sub-magnet located below it, but the outer diameters of different levels of sub-magnets can be different (k is a positive integer less than or equal to n).
[0021] Figure 1 The diagram shows a primary sub-magnet consisting of two coils symmetrical about the midplane, designated "Axial Primary Sub-magnet 1" and "Axial Primary Sub-magnet 2". Each coil contains multiple radially nested solenoid layers, represented by small rectangles in the diagram. Horizontal ellipses "..." indicate several omitted radial layers. Vertical ellipses "..." indicate several omitted axial layers and insulating flanges.
[0022] Each sub-magnet consists of two coils with identical structures and electrical parameters. The two coils use the same wire material and solenoid-stage reinforcement method, and are powered by the same power supply circuit to ensure consistent current waveforms.
[0023] Each coil is provided with a positive terminal connector and a negative terminal connector. The positive terminal connector is located at the end of the innermost solenoid of the coil and is connected to the positive power supply via a copper busbar nested in an insulating flange. The negative terminal connector is located at the end of the outermost solenoid of the coil and is directly connected to the negative power supply.
[0024] It can be seen that this wiring method allows the current to flow radially from the inside to the outside, which is beneficial to optimizing the electric field distribution and can also effectively avoid electromagnetic interference and mechanical stress concentration introduced by external wiring. At the same time, the positive electrode is led out through a copper busbar nested in the insulating flange, which improves the insulation reliability under high voltage and helps to improve the operational stability of the system.
[0025] In this embodiment, compared with the sub-magnet coil reinforcement layer with a low axial order, the sub-magnet coil reinforcement layer with a high axial order has a smaller average angle between the fiber winding direction and the axial direction, a thinner average thickness, a higher axial load-bearing capacity, and a lower radial load-bearing capacity.
[0026] Sub-magnets with higher axial order have larger inner diameters, outer diameters, and heights, and the conductors used in the internal solenoids have higher conductivity, lower ultimate tensile strength, and larger cross-sectional areas.
[0027] For example, a pulse magnet consisting of two axial sub-magnets has a coil with an inner diameter of 12 mm and a height of 100 mm for each axial sub-magnet. It contains 16 radial solenoids wound with copper wire of 3 mm × 5 mm cross-sectional area. Each solenoid coil is reinforced with Zylon fiber composite material wound at 90° with a single bundle fiber tension greater than 120 N (e.g., 140 N) and a fiber fill factor of 80%. The thickness of the reinforcing layer first increases and then decreases radially. The reinforcing layer of the radial 6th stage solenoid is the thickest, at 7 mm, while the reinforcing layer of the radial 1st and 16th stage solenoids is the thinnest, at 2 mm. The average thickness of the reinforcing layer of the 16th stage solenoid is 6 mm. The inner diameter of each coil of the axial secondary sub-magnet is 30 mm and the height is 300 mm. It includes 25 stages of radial solenoids wound with copper wire with a cross-sectional area of 5 mm × 10 mm. Each stage of the solenoid is reinforced by glass fiber composite material with a single bundle fiber tension of less than 60 N (e.g., 40 N) and wound at 40°. The fiber filling coefficient is 60%. The thickness of the reinforcing layer first increases and then decreases radially. The reinforcing layer of the radial 6th stage solenoid is the thickest, at 7 mm, while the reinforcing layer of the radial 1st and 16th stage solenoids is the thinnest, at 2 mm. The average thickness of the reinforcing layer of the 16th stage solenoid is 4 mm.
[0028] In this magnet, the first-stage axial sub-magnet experiences approximately 100 tons of radial electromagnetic force and 10 tons of axial electromagnetic force, while the second-stage axial sub-magnet experiences approximately 40 tons of radial electromagnetic force and 60 tons of axial electromagnetic force. The first-stage axial sub-magnet's reinforcement layer employs high-tension 90° winding and utilizes high-strength Zylon fibers with low impregnation characteristics with epoxy resin, resulting in extremely high radial load-bearing capacity and extremely low axial load-bearing capacity. The second-stage axial sub-magnet's reinforcement layer employs low-tension 40° winding and utilizes medium-strength glass fibers with high impregnation characteristics with epoxy resin, resulting in moderate radial load-bearing capacity and extremely high axial load-bearing capacity. This axially and radially bidirectional graded reinforcement perfectly matches the electromagnetic force characteristics of each stage of the axial sub-magnet, easily achieving a 70T load while maintaining an end axial displacement of less than 2mm, significantly improving the magnet's lifespan. In traditional pulse magnets with single radial graded reinforcement, if the inner diameter is 12mm, even if the outer diameter, height, and reinforcement layer thickness of the magnet are changed, it is difficult to achieve a 70T load while keeping the end axial displacement below 2mm.
[0029] In this embodiment, the fiber winding direction of the reinforcing layer is set according to the distribution of electromagnetic force. The first-level sub-magnets near the mid-plane are subjected to a larger radial electromagnetic force, and the fiber winding direction of their reinforcing layer is at 90° with the magnet axis to maximize the resistance to radial electromagnetic force. The axial electromagnetic force of each level of sub-magnets far from the mid-plane is significantly enhanced. Therefore, the angle between the fiber direction of the corresponding reinforcing layer and the magnet axis is an acute angle, such as 30~80°. This reinforcement method provides strong axial tensile strength. Through the bidirectional graded reinforcement of the shaft diameter, the strength of the entire magnet structure matches the actual stress.
[0030] Correspondingly, in this embodiment, the solenoids of different sub-magnets can be reinforced using different fiber composite materials. That is, the type of fiber material, winding tension, angle, and thickness of each reinforcing layer distributed along the axial and radial directions can vary, determined by the combined radial and axial electromagnetic forces acting on the internal solenoid conductors. For example, the first-level sub-magnet, closer to the central plane of the magnet, experiences higher radial stress and can be reinforced with circumferential winding using Zylon fiber composite material with a strength up to 4.6 GPa; while the second-level sub-magnet, located on the outer side, experiences higher axial stress and can be reinforced with HS-6 Glass fiber composite material, with the fiber winding direction at 60° to the axis. The same reinforcing fiber material is typically used for each radial layer of solenoids within the same sub-magnet.
[0031] The cross-sectional dimensions and materials of the conductors used in solenoids of different sub-magnets can vary. For example, the solenoids of each stage of a first-stage sub-magnet are made of CuNb alloy conductors, while the solenoids of a second-stage sub-magnet are made of CuCrZr alloy conductors. Within the same sub-magnet, the cross-sectional dimensions of the conductors used in solenoids of different radial stages remain consistent.
[0032] The number of radial stages of solenoids contained in the coils that make up each sub-magnet can be different. For example, a first-level sub-magnet is close to the center of the magnet, and each of its coils can contain 14 stages of radially nested solenoids. A second-level sub-magnet is far from the center of the magnet, and is subjected to greater axial electromagnetic compressive force and smaller radial electromagnetic expansion force. Each of its coils can contain 20 stages of radially nested solenoids.
[0033] Preferably, the cross-sectional shape of the conductor is rectangular or circular; more preferably, the cross-sectional width of the rectangular conductor is 1~15mm and the height is 2~30mm; the cross-sectional diameter of the circular conductor is 1~20mm.
[0034] To balance current-carrying capacity and structural stability under strong magnetic fields, this embodiment uses high-strength, high-conductivity wire materials. Preferably, the conductors used in the solenoids of each sub-magnet have a conductivity greater than 40% IACS and an ultimate tensile strength greater than 200 MPa; more preferably, the conductivity is greater than or equal to 70% IACS and the ultimate tensile strength is greater than or equal to 250 MPa.
[0035] In practice, the first-level sub-magnet includes two symmetrically arranged coils, located on opposite sides of the central plane of the magnet. Each coil contains fourteen coaxial, concentric, radially nested solenoids. Each solenoid is wound with CuNb alloy wire with a cross-sectional size of 3mm × 5mm and reinforced with Zylon fiber composite material wound in a circumferential manner with high tension (single bundle fiber tension greater than 120N). The fiber filling factor is 85%. All twenty-eight solenoids of the first-level sub-magnet are connected in series to form a single electrical circuit.
[0036] The secondary sub-magnet also includes two symmetrically arranged coils, which are placed on both sides of the axial primary sub-magnet. Each coil contains twenty coaxial, concentric, radially nested solenoids. Each solenoid is made of CuCrZr alloy wire with a cross-sectional size of 5mm×7mm, and reinforced by HS-6 Glass fiber composite material wound at a 60-degree angle to the axis with low tension (single bundle fiber tension less than 60N). The fiber filling factor is 60%. The twenty solenoids of each coil are connected in series to achieve the integrity of the local current path.
[0037] The pulse magnet of this invention employs a hierarchical independent power supply and timing-coordinated control strategy. The two coils of the secondary sub-magnet are connected in series and powered by a 14.4 MJ capacitor with a charging voltage of 25 kV. Their discharge switches close synchronously to ensure consistent current in both circuits. Similarly, the two coils of the primary sub-magnet are connected in series and powered by a 1.6 MJ capacitor with a charging voltage of 25 kV. The closing time of its discharge switch is delayed, ensuring that the current in the primary and secondary sub-magnet circuits reaches their peak values synchronously during discharge. This achieves effective superposition of the two magnetic field waveforms. The current and voltage waveforms during the magnet discharge process are as follows: Figure 2 As shown in the figure: i 1 represents the current in the first-stage sub-magnet loop. i 2 represents the current in the secondary sub-magnet loop. u 1 represents the voltage across the energy storage capacitor in the first-stage sub-magnet circuit. u 2 represents the voltage across the energy storage capacitor in the secondary sub-magnet circuit. As can be seen from the figure, the discharge current of the two axial sub-magnets can reach the peak value simultaneously, achieving effective superposition of the peak value of the central magnetic field. Compared with the traditional axial single-stage magnet, the discharge characteristics are not degraded.
[0038] In a specific embodiment of the present invention, taking a two-stage sub-magnet as an example: Under a discharge voltage of 24kV, the first-stage sub-magnet can generate a pulsed magnetic field in the central region with a peak magnetic field strength of 70T and a pulse width of approximately 100ms. This magnetic field is dominated by an axial component, with a maximum value of 100T, while the radial component is lower, with a maximum value of only 7.5T (e.g., ...). Figure 3 and Figure 4 Since the pulse width of this sub-magnet is only 100ms, the requirements for temperature rise are not high, and the requirements for the conductivity of the conductor are relatively low. Therefore, considering both the requirements for radial load bearing and temperature rise, CuNb alloy, which has strong load bearing capacity but relatively poor conductivity, was selected as the conductor material for the primary sub-magnet. Its tensile strength (UTS) is as high as 800MPa, and its conductivity is approximately 70% IACS. At the same time, the reinforcement layer adopts Zylon fiber composite material with high tension circumferential winding and a fiber filling coefficient of 85%, with a circumferential strength as high as 4.6GPa, which significantly improves the structure's resistance to deformation under huge radial electromagnetic forces.
[0039] Under a discharge voltage of 25kV, the secondary sub-magnet can generate a pulsed magnetic field with a peak magnetic field strength of 30T in the central region. The axial and radial components of this magnetic field are significant, with maximum values of 52T and 20T, respectively (e.g., ...). Figure 3 and Figure 4 Therefore, this sub-magnet is subjected to both significant radial and axial electromagnetic forces. Due to the sub-magnet's pulse width of 300ms, the temperature rise effect is significant, placing higher demands on the conductivity and heat dissipation capacity of the conductor. Therefore, considering both electromagnetic load bearing and temperature rise requirements, the solenoid of the secondary sub-magnet uses a CuCrZr alloy with moderate load bearing capacity and relatively high conductivity as the conductor material, with a tensile strength (UTS) of 500MPa and an electrical conductivity of approximately 90% IACS. Simultaneously, the reinforcement layer uses HS-6 Glass fiber composite material wound at a 60-degree angle to the axis with low tension and a fiber filling factor of 60%. This composite material has moderate radial load bearing capacity and high axial load bearing capacity, with an axial strength of 250MPa, ten times that of traditional high-tension circumferentially wound Zylon fiber composite reinforcement layers, significantly improving its resistance to axial electromagnetic forces.
[0040] The magnetic field waveform at the central hole of this ultra-strong magnetic field pulse magnet (a cylindrical cavity located at the geometric center of the magnet, formed by coaxial nesting of various sub-magnets, with a diameter equal to the smallest inner diameter among all sub-magnets) is as follows: Figure 6 As shown, the peak value is 100T. The stress distribution at the peak value is as follows. Figure 6 As shown, all axial and radial reinforcement layers are within the safe stress range. Specifically, the maximum stress of each radial reinforcement layer of the first-stage sub-magnet is 3.5 GPa, which is 75% of its ultimate stress; the maximum stress of each radial reinforcement layer of the second-stage sub-magnet is 2.8 GPa, which is 80% of its ultimate stress. The magnets were pre-cooled in a liquid nitrogen environment before discharge, and the temperature reached its maximum value after discharge. Figure 7 The maximum temperature is 55℃, which is below the upper limit of the material's allowable temperature. It can be seen that the two-stage sub-magnets working together can generate a pulsed magnetic field with a peak value exceeding 90T and a pulse width in the millisecond range at the center of the magnet. Figure 8 and Figure 9 , Figure 8 The diagram shows the axial displacement contour plot of the magnet at the peak moment, indicating that the maximum axial displacement of the end conductor is 2.6 mm, which is significantly lower than the maximum axial displacement of a traditional radially graded reinforced 100T magnet. Figure 9 The displacement was reduced by 70%, effectively alleviating the structural damage caused by excessive end displacement and significantly improving the reliability and reusability of the magnet.
[0041] It is evident from the above that the axially bidirectional graded reinforced pulse magnet provided in this embodiment achieves efficient magnetic field superposition through axially symmetrically stacked multi-level sub-magnets, each sub-magnet containing two symmetrically arranged coils and multi-level coaxial and radially nested solenoid structures. The first-level sub-magnet located near the central plane of the magnet uses circumferentially wound fibers as a reinforcement layer, effectively resisting the radial electromagnetic force in this area. The remaining sub-magnets far from the central plane of the magnet use obliquely wound fibers as reinforcement layers, significantly improving the axial load-bearing capacity. This effectively compensates for the deficiency of insufficient axial strength in the end area caused by traditional single reinforcement methods, and also avoids the problem of passively increasing the thickness of the reinforcement layer near the magnet end to resist the huge radial electromagnetic force near the central plane of the magnet, thereby reducing the contribution of the end area conductor to the central field. At the same time, each level of solenoid is wound with the same conductor, ensuring reliable electrical connection. Therefore, this invention not only solves the technical problem of structural damage caused by excessive axial displacement at the end of traditional pulse magnets, but also achieves stable operation and high repetitive discharge at high field strengths of over 90T, greatly improving the reliability and reusability of the magnet.
[0042] In the above embodiment, a support member is provided between the primary sub-magnet and the secondary sub-magnets on both sides. The support member is used to provide a flat axial support surface for the portion of the secondary sub-magnet that is radially outside the primary sub-magnet.
[0043] Specifically, the support can be a ring-shaped rigid structure, whose inner contour matches the outer contour of the first-stage sub-magnet to form a coaxial nested fit, so as to provide uniform radial constraint and axial support.
[0044] An insulating flange is installed between adjacent sub-magnets to ensure that each sub-magnet is tightly stacked without axial gaps.
[0045] In this embodiment, "no axial clearance" means that the gap between the sub-magnets is less than 0.1 mm, which is insufficient to cause discharge impact or local stress concentration. Preferably, the thickness of the insulating flange between each level of sub-magnet is less than 30 mm (e.g., 5 mm), which can ensure sufficient electrical insulation and also provide good mechanical support performance.
[0046] The insulating flange has good electrical insulation and mechanical properties; preferably, the breakdown voltage per millimeter of the insulating flange is greater than 5kV and the bending strength per millimeter of the insulating flange is greater than 50MPa; more preferably, the insulating flange is made of F881A epoxy glass cloth laminate.
[0047] In this embodiment, the insulating flange is provided with a central through hole, the center of which is located on the magnet axis, and its diameter is not less than the smallest inner diameter of each sub-magnet, so as to ensure that the sample rod passes smoothly along the magnet axis and the sample for pulsed magnetic field test is placed at the center of the magnet; the outer diameter of the insulating flange is not less than the largest outer diameter of each sub-magnet, that is, the area of the insulating flange is larger than the largest area of each sub-magnet in the axial direction, which can ensure that the insulating flange can completely cover the end face of each sub-magnet.
[0048] In summary, the axially bidirectional graded reinforced pulse magnet provided in this embodiment, through axially symmetrically stacked multi-level sub-magnets, each sub-magnet containing two symmetrically arranged coils and multi-level coaxial and radially nested solenoid structures, and each solenoid having a high-strength fiber composite material reinforcement layer wound circumferentially on its outer surface with a wire, achieves precise adaptation to the complex electromagnetic forces in the pulsed magnetic field. The mid-plane region is dominated by radial forces and is reinforced with high-tension circumferentially wound Zylon fiber composite material; the end region has both axial and radial forces, and fibers with better impregnation properties (such as Glass fiber) can be selected, and the winding tension, angle, or thickness can be adjusted to enhance the axial load-bearing capacity. This breaks the limitations of traditional single reinforcement layer designs, significantly reduces the axial displacement of the end wires, effectively alleviates the problem of easy end damage, and greatly improves the reliability and reusability of the magnet.
[0049] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. A pulse magnet with bidirectional graded reinforcement of shaft diameter, characterized in that, include: A multi-level sub-magnet stacked along an axial direction, wherein the multi-level sub-magnets are symmetrically distributed about the plane in the magnet; Each of the sub-magnets comprises two symmetrically arranged coils, each coil consisting of multiple coaxial and radially nested solenoids; Each stage of the solenoid is wound sequentially from the same conductor, and each stage of the solenoid has a high-strength fiber composite material reinforcement layer on its outer surface; wherein, the fiber winding direction of the first-stage sub-magnet reinforcement layer closest to the plane of the magnet is at a 90° angle to the magnet axis, and the fiber winding direction of the remaining sub-magnet reinforcement layers is at an acute angle to the magnet axis.
2. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 1, characterized in that, An insulating flange is installed between adjacent sub-magnets to ensure that each sub-magnet is tightly stacked without axial gaps.
3. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 2, characterized in that, Each coil is provided with a positive terminal connector and a negative terminal connector. The positive terminal connector is located at the end of the innermost solenoid of the coil and is connected to the positive power supply via a copper busbar nested in an insulating flange. The negative terminal connector is located at the end of the outermost solenoid of the coil and is directly connected to the negative power supply.
4. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 2, characterized in that, The insulating flange is provided with a central through hole, the center of which is located on the magnet axis and its diameter is not less than the smallest inner diameter of each sub-magnet; the outer diameter of the insulating flange is not less than the largest outer diameter of each sub-magnet.
5. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 1, characterized in that, A support member is provided between the primary sub-magnet and the secondary sub-magnets on both sides. The support member is used to provide a flat axial support surface for the portion of the secondary sub-magnet that is radially outside the primary sub-magnet.
6. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 1, characterized in that, The coils of each sub-magnet differ in at least one of the following parameters: inner diameter, outer diameter, height, and number of solenoid stages.
7. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 1, characterized in that, The conductivity of the conductors used in the solenoids of each sub-magnet is greater than 40% IACS, and the ultimate tensile strength is greater than 200MPa.
8. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 1, characterized in that, The ultimate tensile strength of the fiber material in the reinforcing layer is greater than 1 GPa.
9. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 1, characterized in that, Compared to submagnet coil reinforcement layers with lower axial order, submagnet coil reinforcement layers with higher axial order have a smaller average angle between the fiber winding direction and the axial direction, a thinner average thickness, higher axial load capacity, and lower radial load capacity.
10. The pulse magnet with bidirectional graded reinforcement of shaft diameter according to claim 1, characterized in that, Sub-magnets with higher axial order have larger inner diameters, outer diameters, and heights, and the conductors used in the internal solenoids have higher conductivity, lower ultimate tensile strength, and larger cross-sectional areas.